C :

#include <stdio.h>
#include<math.h>
int main()
{
   int m,n,i,j,k;
   while(scanf("%d",&n)!=EOF)
  { m=0;
    k=3;
   if(n<=2)
   printf("N\n");
   else
   {
     for(i=0;i<n;i++)
     {
       m+=k;
       k++;
     }
     if((m-2*n)%2==0)
     printf("Y\n");
     else
     printf("N\n");
   }
  }
}

C++ :

#include<cstdio>
#include<cstring>
#include<cmath>
#include<iostream>
#include<algorithm>
using namespace std;

int main()
{
    int n;
    while(scanf("%d",&n)!=EOF)
    {
        if(n==0)
            return 0;
        if(n%4==0||(3*n-1)%4==0)
            printf("Y\n");
        else
            printf("N\n");
    }


    return 0;
}